Update util.py adding comment

LCS/PyCommon/util.py

@@ -204,6 +204,7 @@ def find_free_port(preferred_port: int=0):
             s.bind(('', preferred_port))
         except OSError as e:
             if e.errno==98: # OSError: [Errno 98] Address already in use
+                # OS will find a available port with bind option 0
                 s.bind(('', 0))
             else:
                 raise